Force lowercase when checking for normalization type.

Signed-off-by: Alexandros Koumparoulis <akoumparouli@nvidia.com>

nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py

@@ -1549,7 +1549,7 @@ def build_transformer_config(self) -> TransformerConfig:
             For attributes in TransformerConfig that are not in the nemo model config, we add custom logic.
         """
 
-        normalization = self.cfg.get('normalization', 'layernorm')
+        normalization = self.cfg.get('normalization', 'layernorm').lower()
         layernorm_zero_centered_gamma = self.cfg.get('normalization', 'layernorm') == 'layernorm1p'
         if normalization == 'layernorm':
             normalization = 'LayerNorm'